Chosen Solution
Hello, My Panasonic Viera LCD that I’ve owned for five years recently has recently developed a problem displaying picture. However, the sound does still work. If I attempt to turn on the television the screen will light up grey but then go dark immediately. The stand by LED light stays a solid red from that point forward. I have attempted leaving it unplugged and then plugging it back in after a couple hours and I still have the same results. I have also tried just about every “hold the power button, the volume button and the stand by button on the remote” tips that have been recommended for similar issues and have still had the same results. I do not think it is the backlight because I have attempted to hold a flashlight to the screen and can not see any picture. I also took off the back panel to check and see if any of the boards looked damaged but everything looked alright to me. The TV model is a TC-50AS530U. I have attached images of the boards below.
@mlb32001 check the voltage on the individual boards. If the output is correct you know it is your backlight array. If the voltages are not then you know the problem is on he individual boards. Use your multimeter and test for the voltage on the test points (TP marked on the boards)Multimeter set to the voltage VDC according to the list . Black probe to ground, red probe to TP. Voltage chart of P-Board VOLTAGE TEST POINT SPECIFICATION 24V TP7407 < 1V 24V ± 1.2V 16V TP7410 < 1V 15.7V ± 0.6V 5VS TP7501 5.2V ± 0.2V 5.2V ± 0.2V PFC TP7201/TP7202 < 340V 390V ± 15V Voltage chart of A-Board VOLTAGE TEST POINT SPECIFICATION PANEL12V TP4097 11.3V - 13V SUB3.3V TP5400 3.16V - 3.48V SUB5V TP5420 4.98V - 5.25V SUB1.5V TP8101 1.45V - 1.57V SUB1.2V TP8100 1.14V - 1.26V STB5V TP5200 4.9V - 5.4V STB3.3V TP5002 3.14V - 3.46V HDMI3.3V TP8000 3.14V - 3.46V Of course, you can also try to measure the voltages on the connectors.
Always remember that you also need a signal to turn the backlight on (BL_ON). No signal no backlight. Let us know what you find
The solid red light is the standby light. With this solid, the TV is not on at all and I would not expect anything on the screen. At a first guess I think that there is a problem being detected by the set and it is shutting down. Since the screen lights up for a short period, the problem may be with the LED supply. If the current draw is too high, the set will shutdown. I’m not sure this will be fixable from a remote location. If I had this set in my shop, I would be checking the LED strips and the power supply first. Dan
